1. Field of the Invention
This invention relates to the boring of holes and more particularly to a device and method for precisely boring holes of a desired size.
2. Description of the Related Art
The precise machining of holes in a work piece to very close tolerances(of the order of 0.0001xe2x80x2) as to diameter is required in a number of applications. Prior art methods and apparatus for achieving this end result generally first bore a hole which is slightly smaller than the desired size. The size of this hole is then measured with a dial indicator, bore gage, air gage or gage pins and the cutting tool is adjusted manually by means of its control adjuster to the final desired hole size and the boring then done. A prior method and apparatus along these lines is described in U.S. Pat. No. 3,044,322 issued Jul. 17, 1962 to George. This prior art approach has the shortcoming is that the operator must use a graduated dial face connected to the adjuster to make the final size setting. This device is somewhat expensive and bulky in construction. Further, the accuracy of the setting is affected by the accuracy of the adjuster and its dial face. Also the friction on the moving parts involved can affect such accuracy. Other prior art boring heads do not have dial faces which operate in conjunction with adjusters and thus are not capable of rapid and accurate adjustment.
The device and method of the present invention provides an improvement over these prior art devices by virtue of the reliability of its accuracy and the simplicity and economy of its design.
In the device of the present invention, a boring tool head has a cutting tool supported by a tool holder which can be moved relative to a centerline by means of an adjuster. A hole slightly smaller in size than a final hole to be bored is first bored and its size precisely measured. A fitting employing a clamping device is then tightly and securely clamped onto the tool head by means of a clamping lever operating in conjunction with a swivel guide. A position sensor mounted on the clamping device abuts against the movable tool head, a position indicator being provided to receive an output signal from the sensor. The indicator is first set to xe2x80x9czeroxe2x80x9d and the boring tool holder adjuster then set to bring the boring head to the desired location to enable the boring of a hole of the desired dimension.
It is therefore an object of this invention to provide a simple and economical device and method for the accurate boring of a hole of a precisely determined size.
It is a further object of this invention to avoid inaccuracies in the precision boring of holes in a work piece.
Other objects of the invention will become apparent from the following description taken in connection with the accompanying drawings.